Action control device, action control method, imaging device, and program to reduce focus lag

1. An action control device, comprising: a variable-transmittance neutral density (ND) filter configured to have transmittance that varies according to an applied voltage; an applied voltage control unit configured to control the applied voltage, applied to the variable-transmittance ND filter; a diaphragm control unit configured to control illuminance through a diaphragm; and an operation detection unit configured to detect a push operation associated with the action control device, wherein the push operation corresponds to an instruction for imaging preparation or imaging, wherein in an event of the detection of the push operation in a state of monitoring, the action control device switches from the state of monitoring to a state of imaging preparation or to a state of imaging, wherein, in the state of monitoring, prior to the detection of the push operation, the illuminance is controlled such that the applied voltage control unit applies a minimum applied voltage, corresponding to an inactive state of the variable-transmittance ND filter, to the variable-transmittance ND filter, and the diaphragm control unit opens or closes the diaphragm, and wherein, in the state of imaging preparation or in the state of imaging, subsequent to the detection of the push operation, the illuminance is controlled such that the applied voltage control unit applies a certain applied voltage to the variable-transmittance ND filter, which is in the inactive state, to control the transmittance based on the certain applied voltage, and the diaphragm control unit performs control such that the diaphragm enters a fully opened state.

2. The action control device according to claim 1 , further comprising: an imaging unit configured to image an image through the variable-transmittance ND filter; a transmittance calculating unit configured to calculate the transmittance of the variable-transmittance ND filter based on illuminance of the image imaged by the imaging unit; and an applied voltage storage unit configured to store an applied voltage corresponding to transmittance of the variable-transmittance ND filter, wherein, at the time of imaging preparation or at the time of imaging, the applied voltage control unit performs control such that, among applied voltages stored in the applied voltage storage unit, an applied voltage corresponding to the transmittance calculated by the transmittance calculating unit is applied to the variable-transmittance ND filter.

3. The action control device according to claim 1 , wherein the variable-transmittance ND filter is a liquid crystal ND filter.

4. The action control device according to claim 1 , wherein the transmittance of the variable-transmittance ND filter increases or decreases as the applied voltage increases.

5. An action control method of an action control device including a variable-transmittance neutral density (ND) filter having transmittance that varies according to an applied voltage, the method comprising: performing an applied voltage control process of controlling the applied voltage, applied to the variable-transmittance ND filter; performing a diaphragm control process of controlling illuminance through a diaphragm; and performing an operation detection process of detecting a push operation associated with the action control device, wherein the push operation corresponds to an instruction for imaging preparation or imaging, wherein in an event of the detection of the push operation in a state of monitoring, a switch process of switching the action control device from the state of monitoring to a state of imaging preparation or to a state of imaging is performed, wherein, in the state of monitoring, prior to the detection of the push operation, the illuminance is controlled such that a minimum applied voltage, corresponding to an inactive state of the variable-transmittance ND filter, is applied to the variable-transmittance ND filter in the applied voltage control process, and the diaphragm is opened or closed in the diaphragm control process, and wherein, in the state of imaging preparation or in the state of imaging, subsequent to the detection of the push operation, the illuminance is controlled such that a certain applied voltage is applied to the variable-transmittance ND filter, which is in the inactive state, and transmittance is controlled based on the certain applied voltage in the applied voltage control process, and the diaphragm is controlled such that the diaphragm enters a fully opened state in the diaphragm control process.

6. A non-transitory computer readable medium having stored thereon, a set of computer-executable instructions, for causing a computer, which controls an action control device including a variable-transmittance neutral density (ND) filter having transmittance that varies according to an applied voltage, to execute steps comprising: performing an applied voltage control process of controlling the applied voltage, applied to the variable-transmittance ND filter; performing a diaphragm control process of controlling illuminance through a diaphragm; and performing an operation detection process of detecting a push operation associated with an action control device, wherein the push operation corresponds to an instruction for imaging preparation or imaging, wherein in an event of the detection of the push operation in a state of monitoring, a switch process of switching the action control device from the state of monitoring to a state of imaging preparation or to a state of imaging is performed, wherein, in the state of monitoring, prior to the detection of the push operation, the illuminance is controlled such that a minimum applied voltage, corresponding to an inactive state of the variable-transmittance ND filter, is applied to the variable-transmittance ND filter in the applied voltage control process, and the diaphragm control is opened or closed in the diaphragm control process, and wherein, in the state of imaging preparation or in the state of imaging, subsequent to the detection of the push operation, the illuminance is controlled such that a certain applied voltage is applied to the variable-transmittance ND filter, which is in the inactive state, and transmittance is controlled based on the certain applied voltage in the applied voltage control process, and the diaphragm is controlled such that the diaphragm enters a fully opened state in the diaphragm control process.

7. An imaging device, comprising: a variable-transmittance neutral density (ND) filter configured to have transmittance that varies according to an applied voltage; an applied voltage control unit configured to control the applied voltage, applied to the variable-transmittance ND filter; a diaphragm control unit configured to control illuminance through a diaphragm; and an operation detection unit configured to detect a push operation associated with the imaging device, wherein the push operation corresponds to an instruction for imaging preparation or imaging, wherein in an event of the detection of the push operation in a state of monitoring, the imaging device switches from the state of monitoring to a state of imaging preparation or to a state of imaging, wherein, in the state of monitoring, prior to the detection of the push operation, the illuminance is controlled such that the applied voltage control unit applies a minimum applied voltage, corresponding to an inactive state of the variable-transmittance ND filter, to the variable-transmittance ND filter, and the diaphragm control unit opens or closes the diaphragm, and wherein, in the state of imaging preparation or in the state of imaging, subsequent to the detection of the push operation, the illuminance is controlled such that the applied voltage control unit applies a certain applied voltage to the variable-transmittance ND filter, which is in the inactive state, to control transmittance based on the certain applied voltage, and the diaphragm control unit performs control such that the diaphragm enters a fully opened state.